The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Hybrid powertrain systems include internal combustion engines and one or more non-combustion torque machines coupled to a transmission device. Such powertrain systems may transmit torque originating from the engine and the non-combustion torque machine(s) through the transmission device to an output member that may be coupled to a driveline for tractive effort. Control systems for operating such powertrain systems operate the torque-generative devices and apply torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, driveability, and other factors. The non-combustion torque machines may include electric machines that are operative as motors or generators to generate a torque input to the transmission independently of a torque input from the internal combustion engine. The torque machines may transform vehicle kinetic energy, transferred through the vehicle driveline, to electrical energy that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed.